The invention described herein relates generally to organic waste treatment systems, and more particularly to an aerobic composting or humus toilet system which uses controlled solar heating coupled with controlled air and moisture flow to accelerate, augment, and render more efficient the composting process, and to transform human excrement, organic kitchen, and/or garden materials into a valuable, nutrient-rich fertilizer and soil conditioner.
Whatever the advantages, there are several significant problems associated with the use of the well-known flush toilet and attendant sewer systems. For example, it is widely thought that such toilets are terribly wasteful of clean water. Typically, five gallons of drinkable water are dumped into the sewer system each time such toilets are flushed. In fact, the average person flushes five times a day, contaminating 9000 gallons of drinking water in a year at a cost of $18-45. All of this is done to process what ends up as 75-100 pounds of humus in a properly operating composting toilet. The usual ratio is approximately 100 parts by volume of clean water mixed with one part of human excrement. The water-excrement mixture is then transported to a central treatment facility where efforts, usually unsuccessful, to separate the two components take place. In other arrangements, the water-excrement mixture passes into cesspools or septic tanks, where the two components are also ultimately to be separated. Contaminated water also leaks out of sewer systems on its way to treatment facilities and even after treatment remains contaminated to some extent. The result is often the pollution of underground water supplies and wells and the contamination of lakes, rivers, coastal regions, and other waterways. There are also major problems associated with the disposal of the sludge that results from the treatment process required by sewer systems and the septage that remains after septic tank treatment. Both systems consume large quantities of clean water. Indeed, the very nature of water-borne waste treatment systems is such that 60-90% of the cost is in the pipes and pumps used to transport the material to the treatment site.
There are many areas that do not conveniently lend themselves to either sewer or septic systems, for example, locations remote from concentrations of population, islands and hilly or mountainous regions where the soil absorption is poor. Various forms of toilets have been used in such areas. In some regions, excrement is deposited in tanks which are from time to time removed by helicopter so that their contents may be treated at more conventional purification plants. There are also commercially available a number of composting toilets. Such toilets do address the water supply and ground and water contamination problems associated with flush toilets, and they are sometimes suitable alternatives for sewer or septic systems. However, the use of such commercially available composting toilets has brought with it its own problems. It is desirable that the decomposition processes used in such toilets be aerobic in nature (as opposed to anaerobic), but that is a goal more easily stated than actually obtained. Frequently, the decomposition processes are or become anaerobic in nature and produce thereby foul stenches, the possibility of a public health hazard from the spread of disease by pathogens that survive longer in an anaerobic decomposition process and environment and soil contamination from the leakage of an ammonia by-product. Some toilets, ostensibly aerobic, are only aerobic at or near the surface of the decomposing bio-mass. In addition, such systems typically do not work well (or at all) in cool or humid environments. In all cases, when anaerobic conditions occur a buildup of an excessive amount of liquid due to the inability of the system to effect its evaporation is observed. To meet this problem, electrical heat is sometimes provided, but its benefits are also often lost to cooler ambient air. As a result, in cool or cold temperatures biological activity slows or halts and instead of composting, in which input is reduced to approximately 5 to 10% of its original volume, one has a holding tank with little or no volume reduction. The contents of such tanks must, of course, be removed and further treated before they can safely be disposed of or returned to the earth.
In dry or warm climates the bio-mass will dry out too fast in the processing by available systems (including those using electric heat). This situation, although not as objectionable as anaerobic conditions, results in a bio-mass that has not been stabilized through the biochemical and digestive part of the composting process. This results in an end product that has additional biological activity when rewetted and will provide a breeding ground for disease vectors and, if left wet, will further decompose anaerobically, creating objectionable odors.
In general, energy introduced into the presently available composting toilets is generally uncontrolled and is frequently lost to the surroundings without performing the useful function of evaporation of excess liquid. In some instances, too uncontrolled energy is allowed through the bio-mass, rendering it dry and unstabilized.
The existing designs do not satisfactorily address the necessity for control of temperature, bio-mass moisture content, aeration, the carbon-to-nitrogen ratio and pH, nor do they allow for variable environmental conditions.